--This fiscal year, we continued our studies of our gene knockouts (KO) of the mouse oxytocin (Oxt) and vasopressin (Avp) 1b receptors (Oxtr and Avpr1b, respectively) to investigate their specific roles in mediating behavior. Avp and Oxt are neurohormones that are best known for their peripheral actions in regulating salt and water balance, blood pressure, lactation and parturition. However, numerous pharmacological studies have implicated these hormones in various behaviors as well, including aggressive, affiliative, social recognition, fear conditioning and maternal. --We continued our studies of the CA2 region of the hippocampus where the Oxtr and Avpr1b are located. The CA2 area is an important, although relatively unexplored, component of the hippocampus. We are studying the role of various receptors and in the CA2 by crossing floxed receptor lines with Oxtr and Avpr1b-cre expressing lines. We are studying the resultant behaviors, especially as they relate to aggression and learning and memory. --We re-tooled the laboratory to use additional modern neuroscience techniques. Specifically, we started using optogenetics and began to acquire the tools needed for electrophysiology and endomicroscopy for studying the CA2's role in social behavior and memory. We are applying these tools in combination with our knockout mice to see how cell firing patterns differ between normal and knockout mice in response to various social situations.